Penn I actually give him a better chance than last fight, just because he has applied himself for a long time now. And if he bulked up properly for the weight class and trained accordingly I think he would do better than last time.
GSP – although he outstrikes fighters who would supposedly outstrike him, it’s probably not in Silva’s class. Weight gain or not, he would have a disadvantage there, but his solid takedowns could give Silva a hard time. And GSP has said he walks around at 184, but might be hard to bulk up. Even so, this i think because of GSP's well rounded skills this could be a closer match for Silva than his previous fights.
Silva- hmm how about 0 chance, at best. Brock is to fast, strong, big, powerful and would just steamroll over Silva at the opening and hammerfist it out. Size makes a difference and this is a HUGE gap, 2+ weightclasses (i say 2+ because brock fights at well over 265, reportedly at 285).